This application claims the priority of International Application No. PCT/DE2009/001280, filed Sep. 9, 2009, and German Patent Document No. 10 2008 047 043.0, filed Sep. 13, 2008, the disclosures of which are expressly incorporated by reference herein.
The invention relates to a replacement part for a gas turbine blade, a gas turbine blade as well as a method for repairing a gas turbine blade.
As is known, in the field of gas turbines, particularly in the field of aircraft engines, the blades of the rotors of a compressor or a turbine get damaged after a specific utilization or from the effect of foreign bodies.
The so-called patching has gained acceptance in the case of integral rotors, such as BLISK (Germanization of “bladed disk”) or BLING (Germanization of “bladed ring”) in order to avoid having to replace the entire rotor or to avoid having to replace complete blades in the case of rotors having individual, separate blades. In the case of patching, a section of a blade is first removed and then replaced by a replacement part section. This is normally accomplished by welding on a replacement part section after the blade section has been removed. The replacement part section in this case, may already have the exact dimensions of the to-be-replaced section; however, normally the replacement part section has a certain excess, which will be removed in the course of post-processing to achieve the desired geometry. Depending upon the blade material and/or blade geometry, welding defects in the form of cracks may arise due to unfavorable conditions at the transition between the patch and blade.
With this as the background, the object of the invention is establishing a possibility to create repaired gas turbine blades with an almost defect-free welded connection.
Thus, a replacement part for a gas turbine blade is in particular provided. The gas turbine for this gas turbine blade or to which this gas turbine blade belongs may be configured as an aircraft engine for example. The replacement part is designed in particular to replace a to-be-replaced, removed portion of the gas turbine blade. In this case, the to-be-replaced portion features a section of the blade tip and a section of at least one edge. This edge is an edge, which belongs to a group of edges, wherein this group of edges includes the leading edge and the trailing edge of the gas turbine blade. The replacement part furthermore has at least one side, which may be designated or is designated as the joining side. This joining side of the replacement part is the side of the replacement part, with which the replacement part can be brought into contact with the gas turbine blade or the blade remnant or the blade stub that is reduced by the removed portion and joined to this gas turbine blade. For example, the replacement part may be configured like a type of triangle, wherein one side is provided for configuring an edge or an edge section, in particular a leading edge or trailing edge or section thereof, and wherein a different side is provided for configuring the blade tip or a section of the blade tip, and wherein a third side, which is different than the two aforementioned ones, is configured as the joining side. In this case, it may be provided that there is an excess in the region of the to-be-formed leading or trailing edge and/or in the region of the to-be-formed blade tip and, if applicable, in other regions.
It is provided pursuant to the invention that the joining side have at least one first section, in which this joining side is U-shaped in cross section.
In this case, it may be provided that the joining side is U-shaped in cross section continuously along this side. However, it may also be provided that the joining side is only U-shaped in sections or partially along its side. The U-shape is in particular such that it forms a base or bottom as well as two flanges or walls running on both sides of this base or bottom. It may be provided that the base or the bottom in this case is configured to be flat or is configured to be essentially flat. Furthermore, it may be provided that the walls or flanges having the U-shape are equally wide, and namely as viewed in the longitudinal direction of extension of the joining side. However, it may also be provided that the walls that form the U-shape are of different widths in the longitudinal direction of extension of the joining side. The latter may be the case for example with a preferred embodiment in which, attached to the first section, which forms a U-shape in cross section, is a second section of the joining side, which is L-shaped in cross section. In the case of such an embodiment, the one U-shaped flange is no longer in the region of the L-shape, while the other flange passes through to form the L-shape.
In the case of an embodiment, in which the cross sections of the joining side change along the joining side, it may be provided that a U-shape is provided in sections and an L-shape is provided in sections. In this case, it may be provided that the U-shape and the L-shape are directly adjacent to one another.
It is provided in an especially preferred embodiment that the walls or flanges, which run on both sides of the base of the U-shape, are such that at least one of these walls or one of these flanges has a thickening of its wall thickness. This may be such that the thickening of the wall thickness is given as compared to the other flange.
It may also be provided that thickening is present as related to the wall thickness of the same wall. Such an embodiment with a thickening may be provided if the joining side is continuously U-shaped in cross section. Such an embodiment with a thickening may also be provided with a design in which the cross section of the joining side is U-shaped in sections and L-shaped in sections. In this case, it may be provided, for example, that the thickening is present in the region of the flange with the L-shape.
In an advantageous embodiment, at least one flange, which is provided to form the U-shape and is provided without lengthening such a flange with a U-shape, is configured such that it, as viewed in the longitudinal direction of joining side, has at least one region, in which the flange extends longer in the direction as viewed transverse to the base of the U-shape and transverse to the longitudinal direction of joining side than in another region located in the direction of this longitudinal side. These length differences exist in particular in the direction which is located perpendicular to the base and perpendicular to the addressed longitudinal extension direction of the joining side. It may be provided, for example, that a bend be provided on a flange end facing away from the base in its progression in the longitudinal direction of the joining side.
In an advantageous embodiment, the joining side essentially runs straight along its longitudinal direction of extension. It may also be provided that the joining side is in some sections U-shaped in cross section and in some sections L-shaped in cross section, and a region is provided between this L-shape and U-shape (as viewed in the direction of the joining side) that is configured to be neither U-shaped nor L-shaped.
Furthermore a gas turbine blade, particularly a blade for an aircraft engine, is provided. The gas turbine blade has a blade stub or a blade remnant and replacement part formed on this blade stub or on this blade remnant via a welded connection. The replacement part may be configured for example in a manner that is in accordance with the invention.
It may be provided that the second section that is L-shaped in cross section be adjacent on one edge of a group of edges, which group of edges includes the leading edge and the trailing edge of the gas turbine blade.
However, it may also be provided that the region of the flange forming the thickening of the wall thickness is adjacent to an edge of a group of edges, which group of edges includes the leading edge and the trailing edge of the gas turbine blade.
Furthermore, it may be provided that a region, in which the side of an L-shaped or a U-shaped flange facing away from the base is removed further from this base than in another region spaced apart in the longitudinal direction of the joining side, is adjacent on an edge of the group of edges, which group of edges includes the leading edge and the trailing edge of the gas turbine blade.
The invention is described in more detail in the following in terms of exemplary embodiments without restricting the invention thereto.